Pretreatment and dyeing of shaped articles derived from wholly aromatic polyamides

ABSTRACT

Processes are disclosed for the conversion of thermally stable shaped articles derived from wholly aromatic polyamides into level dyeing, deeper dyeing products having improved resistance to discoloration by sunlight or ultraviolet radiation. The processes involve treatment of the shaped articles at elevated temperatures at atmospheric pressure under carefully controlled conditions, and include a pretreatment or conditioning treatment carried in a hot bath of a high boiling organic liquid followed by dyeing the shaped articles in another hot bath cotaining a conventional organic dyestuff dissolved or dispersed in a high boiling organic liquid which may be the same or a different high boiling organic liquid. High boiling glycols, glycol ethers, solvents or solvent blends are especially suitable. Additionally, the hot dyebath preferably includes a further additive to minimize the effect of harmful radiation. The processes may be carried out batchwise or continuously, and may be employed for the treatment of the shaped article in the form of continuous filament yarn, staple yarn, tow, fabric, etc. Special features of the invention are the relatively short time of treatment (especially in the case of continuous operation) thus providing a commercially feasible process and the avoidance of the need for employing solid organic or inorganic pigments for coloring the thermally stable shaped articles.

United States Patent [191 Hermes [111 3,771,949 [4 1 Nov. 13,1973

1 1 PRETREATMENT AND DYEING OF SHAPED ARTICLES DERIVED FROM WHOLLYAROMATIC POLYAMIDES [75] Inventor: Julius Hermes, Martinsville, Va.

[73] Assignee: Martin Processing Company,

Incorporated, Martinsville, Va.

[22] Filed: Nov. 29, 1971 [21] Appl. No.: 203,010

[52] US. Cl 8/4, 8/173, 8/178 R [51] Int. Cl. D06p 5/04, D06p 3/24 [58]Field of Search 8/178 R, 4, 173

[56] References Cited UNITED STATES PATENTS 2,828,180 3/1958 Sertorio8/62 3,510,243 5/1970 Seuret et al 8/174 3,591,327 7/1971 Matsuda et a1.8/178 3,606,988 9/1971 Walz et al 8/173 X 3,674,420 7/1972 'Sapers 8/1733,695,992 10/1972 Moulds 161/178 Primary Examiner-Leon D. RosdolAssistant Examiner-T. .1. Herbert, Jr. AttorneyRichard K. Stevens et al.

[57] ABSTRACT Processes are disclosed for the conversion of thermallystable shaped articles derived from wholly aromatic polyamides intolevel dyeing, deeper dyeing products having improved resistance todiscoloration by sunlight or ultraviolet radiation. The processesinvolve treatment of the shaped articles at elevated temperatures atatmospheric pressure under carefully controlled conditions, and includea pretreatment or conditioning treatment carried in a hotbath of a highboiling organic liquid followed by dyeing the shaped articles in anotherhot bath cotaining a conventional organic dyestuff dissolved ordispersed in a high boiling organic liquid which may be the same or adifferent high boiling organic liquid. High boiling glycols, glycolethers, solvents or solvent blends are especially suitable.Additionally, the' hot dyebath preferably includes a further additive tominimize the effect of harmful radiation. The processes may be carriedout batchwise or continuously, and may be employed for the treatment ofthe shaped article in the form of continuous filament yarn, staple yarn,tow, fabric, etc. Special features of the invention are the relativelyshort time of treatment (especially in the case of continuous operation)thus providing a commercially feasible process and the avoidance of theneed for employing solid organic or inorganic pigments for coloring thethermally stable shaped articles.

4 Claims, No Drawings PRETREATMENT AND DYEING OF SHAPED ARTICLES DERIVEDFROM WIIOLLY AROMATIC POLYAMIDES The present invention relates to amethod for treating or pretreating shaped articles derived from whollyaromatic polyam ides to render them easily dyeable by conventionalorganic dye-stuffs at ordinary atmospheric pressure, a method for dyeingsuch shaped articles with conventional organic dyestuffs, and a methodcombining both the pretreating and the dyeing. Also included is thefeature of incorporating additives that will protect the dyed productsfrom the effect of harmful radiation (e.g., sunlight and/or ultravioletradiation).

BACKGROUND OF THE INVENTION Considerable research effort has beendirected in recent years toward the preparation ofhigh-temperatureresistant wholly aromatic polyamides for use in the formof fibers, yarns, fabrics, paper and films. These polymers have beenfound to be superior to natural and many oher synthetic polymers inretention of desirable properties at elevated temperatures on long-termexposure.

However, wholly aromatic polyamides, in general, are highly crystallineand have what might be called a non-uniform heat history. As a result,they are not considered dyeable. Particularly, the filament yarns arenot even merged for dye-ability. See, e.g., DuPonts Nylon BulletinN-246, May 1971. This is primarily due to the nature of themanufacturing processes used in manufacture of the wholly aromaticpolyamide materials, wherein the filaments after extrusion are subjectedto dry heat. The end-to-end non-uniformity in dry heat application causes structural variations in the filament which in turn results in theundesirable dyeing variations.

Recent efforts to dye wholly aromatic polyamides have primarily involvedaqueous pressure dyeings. However, all of .these processes areexclusively batch operations requiring up to 2 hours of exposure time.Even then very unlevel (i.e., streaky) dyeing is obtained because of thevarying heat history, particularly for those products consisting offilament yarns.

The process of the present invention involves a special pretreatment(preferably but not necessarily continuous) and a special dyeing method(preferably but not necessarily continuous) for shaped articles derivedfrom wholly aromatic polyamides. This is accomplished at atmosphericpressure by the use of glycol or glycol ether fluids and lubricants,solvents and solventblends. The present invention also includes thecombination of the pretreatment and the dyeing.

Many wholly aromatic polyamides discolor when exposed to intensesunlight or ultraviolet radiation. Considerable improvement can beachieved by the incorporation of ultraviolet screeners, colorstabilizers, antioxidantsand other chemicals which reduce the effect ofharmful radiation. Accordingly, this represents still another feature ofthis invention.

SUMMARY OF THE INVENTION It has now been found that when thermallystable wholly aromatic polyamide compositions in the form of fibers,yarns, fabrics, papers, films (or other useful shaped articles having ahigh surface-to-volume ratio) are first pretreated with glycol or glycolether fluid and lubricants, and then subsequently treated with solventsand solvent blends containing dye, ultraviolet screeners, colorstabilizers, antioxidants, etc., at atmospheric pressure at hightemperatures under carefully controlled conditions, one thereby obtainslevel, deep, fast shades.

The optimum time-temperature conditions of both pretreatment and dyeingare somewhat critical in that they are dependent to some extent on thepolymer composition. If treated below a given temperature for a givenpolymer, the desired dyeing will not occur giving streaky (unlevel)dyeing, or it occurs at too slow a rate to be practical; if treated attoo high a temperature or for too long a time in the optimum temperaturerange, the products, although dyed, may become emb rittled and losesomeof their desirable physical properties.

Satisfactory time and temperature conditions for most wholly aromaticpolyamides involve raising the temperature of the heating bath to aboutto 500F, and when reaching the desired temperature causing exposurethereof to the treating bath for less than 1 minute in the case ofcontinuous operation up to about two hours for batchwise operation inorder to complete the treatment. Exposure may alsotake placeduringheating of the bath, although somewhat less desirably.

Accordingly, it is an object of this invention to provide a pretreatmentprocess for the preparation of articles of thermally stable whollyaromatic polyamides having an improved dyeability necessary forobtaining level, deep shades.

Another object of the invention is to provide a process for the leveldyeing of articles of thermally stable wholly aromatic polyamidesformerly not considered dyeable or uniformly dyeable.

Still another object of the invention is to provide a process for thepreparation of articles of thermally stable wholly aromatic polyamideshaving improved durability or resistance to sunlight or ultravioletradiation.

Finally, another object of the invention is to provide a process forincorporating antioxidants and other chemical preservatives whenmanufacturing foodpackaging materials from thermally stable whollyaromatic polyamides.

, Other objects of the invention will become apparent from aconsideration of the following description.

The term wholly aromatic polyamide" as used herein is to be understoodas meaning a high molecular weight synthetic organic polyamide made bythe condens'ation or reaction of aromatic or essentially aromaticmonomeric starting material or materials. Thus, in the case of aromaticdiamines and aromatic diacids (or derivatives of such acids), thepolymer repeating unit structure of the resulting aromatic polyamide inone instance may be illustrated by the following structural formula:

Commercially available examples of such polyamides are the varios DuPontNomex high temperature resistant nylons. These include Nomex 450, astaple fiber or tow (see DuPont Bulletins N-236 of October 1969, N-245of March 1971 and N-249 of June 1971); Nomex 430, a continuous filamentyarn (see DuPont Bulletin N-246 of May 1971); and a modified Nomex E-12Cin staple carpet fiber form.

However, other kinds of suitable wholly aromatic polyamides are known inthe literature, and the present invention is useful for all such otherkinds as well, it being understood that the wholly aromatic polyamidesper se form no part of the present invention.

For a convenient source in the literature of further detailedinformation on the chemistry and the nature of wholly aromaticpolyamides to which this invention is applicable, those interested arereferred to Mark & Gaylord, Encyclopedia of Polymer Science andTechnology, Vol. 10, 1969, pages 583-597. Still further information canbe found in Chapter 6 entitled New Linear Polyamides of a book entitledNew Linear Polymers, by Lee, Stoffey & Neville, 1967, pages l29169. Forbrevity, the relevant contents of the pages cited are to be regarded asincorporated herein by reference.

The high boiling organic liquids employed for pretreatment in accordancewith this invention are the glycols and glycol ethers such as ethyleneglycol, propylene glycol, diethylene glycol, dipropylene glycol,triethylene glycol, tetraethylene glycol, and the monoalkyl and di-alkylethers of these glycols such as the mono-ethyl ether or the di-methylether of any of the foregoing glycols. Preferably, the glycols andglycol ethers are employed in substantially anhydrous form.

The glycols or glycol ethers or solvents or solvent blends may beemployed over a rather wide range of conditions such as temperature andtime of treatment.

For example, temperatures as low as about 140F have been employed aswell as temperatures at or near the boiling point of the treating bath.A preferred maximum is about 500F.

Times of treatment may be varied from as low as about seconds to as highas 60 seconds in the case of continuous operation. In the case of theless preferred batch operation (i.e., less preferred only because lessdesirable from the commercial point of view) longer times, up to 2 hoursare permissible.

Generally speaking, it is preferable to employ a substantially inverseratio between the temperature and the time of treatment; i.e., desirableresults can be obtained with shorter times of treatment the higher thetemperature, and this is one of the especially desirable features ofthis invention from the commercial point of view.

While those skilled in the art will appreciate that rather widevariations in the treating conditions-whose limits have been mentionedabove are permissible, at the same time for any given wholly aromaticpolyamide starting material some slight latitude must be accorded theskilled worker in selecting the optimum conditions within those broadlimits that willgive him the satisfactory dyeing that is a feature ofthis invention.

Any conventional organic dyestuffs (cationic dyes are preferable) whichare dispersible in the solvents and/or solvent blends may be employed,depending on the color and shade desired in the final dyed product.

Likewise, conventional dye assistants and solvents may be employed inthe dye baths. Among these may be mentioned the following solvents aloneand/or blends of two or more such solvents: methyl ethyl ketone,benzaldehyde, tetrahydrothiophene 11 dioxide, dimethyl sulfoxide, benzylalcohol, glycols and glycol ethers, dimethyl phthalate, dimethylformamide, furfuryl alcohol, dimethyl acetamicle, dibenzyl ether,diacetone alcohol, etc.

The invention may be still further illustrated by the following detailedworking examples which however are not intended to be limiting on thescope of the invention.

EXAMPLE I Pretreatment of wholly aromatic polyamide continuous filamentyarn fabric with diethylene glycol, and subsequent dyeing with asolution of ethylene glycol and methyl ethyl ketone in dimethylsulfoxide with the simultaneous application of ultraviolet screener:

Samples of wholly aromatic polyamide woven filament yarn fabric (7 oz.per square yard, two-ply, 200 denier yarn, both warp and fill) werepretreated as follows:

Pretreatment bath of 100.00 percent diethylene glycol at 190C atatmospheric pressure.

The fabric was treated for 20 seconds, after which the samples werewashed in clear water, dried and then dyed as follows:

The dye-bath, at 105C. and at atmospheric pressure, consisted of thefollowing ingredients:

3.0 percent (by vol.) ethylene glycol 10.0 percent (by vol.) methylethyl ketone 87.0 percent (by vol.) dimethyl sulfoxide 10.0 grams perliter basic green, Color Index No. 6

10.0 grams per liter Uvinul D-49 (benzophenone derivative by GeneralAniline & Film Corp.)

The fabric samples were dyed for 40 seconds, after which the sampleswere washed in clear water, dried and then an after scour treatment wasgiven as follows:

The scour bath, at 80C, comprised 5.0 grams/per liter of Hydraphthal(self=emulsified solvent blend from DuPont).

The fabric samples were scoured for seconds, after which the sampleswere washed in clear water, and then flash-dried at 200C.

pressure dyeing, as

described in DuPont Bulletin N-249 of June 1971 American Association ofTextile Chemist & Colorist (AATCC) 8 least break; 1 maximum break 1 Theimprovement in dyeing uniformity and sunlight durability of the fabrictreated according to the present invention just indicated is apparentfrom the above results.

EXAMPLE u Pretreatment of wholly aromatic polyamide staple (2.0 denierper filament, 2 in.) spun yarn fabric with tetraethylene glycol andsubsequent dyeing with a solution of ethylene glycol and methyl ethylketone in dimethyl sulfoxide with the simultaneous application ofultraviolet screener:

Samples of wholly aromatic polyamide woven spun yarn fabric (6 oz. persquare yard) were pretreated for 20 seconds with tetraethylene glycol atatmospheric pressure. The samples were treated under various conditionsof temperature after which the samples were washed in clear water, driedand then dyed as follows:

The dye-bath, at 100C. and atmospheric pressure, was made up as follows:

5.0 percent (by vol.) ethylene glycol 15.0 percent (by vol.) methylethyl ketone 80.0 percent (by vol.) dimethyl sulfoxide 10.0 grams perliter Basic Green, Color Index No. 6

10.0 grams per liter Uvinul D-49 The fabric samples were dyed for 40seconds, after which the samples were washed in clear water, dried andthen an after scour treatment was given as described in Example I.

The results obtained are shown in Table II.

dyeing as described in DuPont Bulletin N-249 of June 1971 'AATCC 8 leastbreak; 1 maximum break All of the above pretreated samples were adjudgedto be better in dyein g uniformity and lightfastness than for untreatedsamples. The improvement in dyeing levelness and sunlight durabilityresulting from the method of the present invention is apparent from theabove results.

EXAMPLE Ill Pretreatment of wholly aromatic polyamide staple (2 in. 2.0denier per filament) spun yarn fabric with diethylene glycol andsubsequent treatment with various blends of ethylene glycol, dimethylacetamide, methyl ethyl ketone, dimethyl sulfoxide, and dimethyl form-The fabric samples were treated for 40 seconds, after which the sampleswere washed in clear water, dried and then an after scour treatment wasgiven as described in Example I.

American Association of Textile Chemist and Colorist AATCC 8 leastbreak; 1 maximum break The above results show that synergistic effectsare obtained by treatment with various solvent blends. It is apparentfrom the above results that improved lightfastness is obtained bytreatment with solvent blends as compared with that obtained by using asingle solvent by itself. This is of practical commercial importance.

EXAMPLE IV Pretreatment of wholly aromatic polyamide staple (2 in., 2.0denier per filament) yarn fabric with various glycols, and subsequenttreatment with a solution of ethylene glycol in dimethyl acetamide withthe simultaneous application of ultraviolet screener:

Samples of wholly aromatic polyamide woven spun yarn fabric (8 oz. persquare yard) were pretreated as shown below in Table IV.

The fabric samples were treated at a temperature of 190C for 20 seconds,after which the samples were washed in clear water, dried and thentreated as follows:

A bath, at 130C. at atmospheric pressure, was made up as follows: r

5.0 percent (by vol.) ethylene glycol 95.0 percent (by vol.) dimethylacetamide 10.0 grams per liter Tinuvin 327 The samples were treated for20 seconds, after which samples were washed in clear water, dried andthen an after scour treatment was given as described above in Example I.

The results obtained are shown in Table IV.

amide with the simultaneous application of ultraviolet TABLE [Vscreeners:

f h n l Sample Pretreatment Fluid Lightfastness' Samples 0 w o yaromatic po yamr e woven spun 40 hours in carbon m yarn fabric (8 oz.per square yard) were pretreated 1 ml 1 l FaSde-Ometer e y ene 3 yet)with diethylene glycol as described in Example I and 2 methylene meal 7then treated as follows: 3 v triethylene glycol 6 TABLE IIIA Percent byvolume Methyl Ultraviolet Ethylene ethyl Dimethyl Dimethyl Dimethylscreener, Antioxidant, Tempera- Snmple number glyc ketone acetamidesulfoxide formamide 10.0 gJIiter 10.0 gJliter ture, C

1 17.0 83.0 Uvinul D-49 130 2 17.0 66.0 ..do 130 3 15.0 80.0 .....d0 45.0 15.0 80.0 .do 101001 02. 100 5 17.0 83.0 Tinuvin 327 1 a 17.0 17.066.0 .do 130 1 Snsbtituted benzotriazole made by Geigy Dyestufis. 2 Madeby Shell Chemical Co.

4 tetraethylene glycol 4 5 Ucon lubricant 4 (polyalkylene glycols andderivatives made by Union Carbide Chemicals &

Plastics 6 (untreated) l *AATCC 8 least break; 1 maximum break The aboveresults show the improvement obtained in lightfastness by pretreatmentwith various glycol fluids.

EXAMPLE V Pretreatment of wholly aromatic polyamide tow with diethyleneglycol, and subsequent dyeing with a solution of ethylene glycol indimethyl acetamide, dimethyl sulfoxide and methyl ethyl ketone with thesimultaneous application of an ultraviolet screener:

Samples of 120,000 denier wholly aromatic polyamide tow (2.0 denier perfilament) was pretreated with diethylene glycol as described above inExample I, after which samples were dyed as shown in Table V.

TABLE V Percent by volume Methyl Sample Temp Ethylene Dimethyl Dimethylethyl number glycol acetamide sulfoxide kctone The tow samples were dyedfor 40 seconds with simultaneous application of Tinuvin 327 (10gm/liter) and then an after scour treatment was given as described abovein Example I.

Good level dyeing was obtained in this manner.

EXAMPLE VI Pretreatment of wholly aromatic polyamide staple (10.0 denierper filament) spun carpet yarn with diethylene glycol, and subsequentdyeing with a solution of ethylene glycol in dimethyl acetamide with thesimultaneous application of ultraviolet screener:

Samples of wholly aromatic polyamide spun carpet yarn (2/1 cotton count)were pretreated with diethylene glycol as described above in Example I,and then dyed as follows:

A dye-bath, at 130C. at atmospheric pressure, was made up as follows:

50.0 percent (by volume) ethylene glycol 48.0 percent (by volume)dimethyl acetamide 2.0 percent (by volume) citric acid 2.0 grams perliter Basic Orange, Color Index No. 22

8.0 grams per liter Tinuvin 327 The yarn samples were dyed for 10seconds, and then an after scour treatment was given as described abovein Example I. Good level dyeing was obtained.

EXAMPLE VII Pretreatment of wholly aromatic polyamide staple spun yarnfabric with triethylene'glycol and subsequent dyeing with a solution oftetrahydrothiophene 1-1 dioxide in dimethyl sulfoxide:

Samples of wholly aromatic polyamide woven spun yarn fabric (8 oz. persquare yard) were pretreated as follows:

The pretreatment bath, at 190C. and atmospheric TABLE VII Sample DyeingLevelness A. Present Invention Excellent B. Conventional aqueouspressure Poor dyeing as described in DuPont Bulletin N-249 of June I971EXAMPLE VIII Pretreatment of wholly aromatic polyamide continuousfilament yarn fabric with tetraethylene glycol, and subsequent dyeingwith a solution of methylethyl ketone in dimethyl formamide with thesimultaneous application of ultraviolet screener:

Samples of wholly aromatic polyamide woven filament yarn fabric (1 oz.per square yard, two-ply 200 denier yarn, both warp and fill) werepretreated with tetraethylene glycol as described above in Example II,and then dyed as follows:

The dye-bath, at C. and atmospheric pressure, was made up as follows:

10.0 percent (by vol.) methyl ethyl ketone 90.0 percent (by vol.)dimethyl formamide 2.5 percent grams per liter BasicBlue, Color Index10.0 grams per liter Uvinul D-49.

The fabric samples were dyed for 60 seconds, and then an after scourtreatment was given as described above in Example I.

The results are shown in Table VIII.

TABLE VIII Sample Dyeing Lightfastness' Levelness 40 hours exposure incarbon are Fade-Ometer A. Present Invention Excellent 7 B. ConventionalPoor I aqueous pressure dyeing as described in DuPont Bulletin N-249 ofJune 1971 "AATCC Scale 8 least break, I maximum break EXAMPLE IXPretreatment of wholly aromatic polyamide staple (2.0 denier perfilament) spun yarn with triethylene glycol, and subsequent dyeing witha solution of methyl ethyl ketone in tetrahydrothiophene l-l dioxide:

Samples of wholly aromatic polyamide woven spun yarn fabric (6 oz. persquare yard) were pretreated with triethylene glycol as described abovein Example VII, and then dyed as follows:

The dye-bath, at F. and atmospheric pressure, was made as follows:

30.0 percent (by vol.) methyl ethyl ketone 70.0 percent (by vol.)tetrahydrothiophene 1-1 dioxide Samples of wholly aromatic polyamidepaper (2.0 mil) were pretreated with triethylene glycol as describedabove in Example 8, and then-dyed as follows:

TABLE XI Percent volume Methyl Ultraviolet Temp Ethylene ethyl DnnethylDimethyl Dimethyl scrooner, bamplo number C glycol ketone acctamidesulfoxide formamidc 10.0 gmJlitor 1. 130 20.0 20.0 00.0 Uvinul D49 2 13020.0 80.0 Do. 100 5.0 15.0 80.0 Do. 4... 100 5. 0 30.0 65.0 Do. 5. 1005.0 15.0 80.0 I Do. 6 130 20.0 80.0 Timuvin 321 7 130 20.0 20.0 60. 0Do.

above in Example I. Good level dyeing was obtained. The paper sampleswere dyed using Basic Blue, Color EXAMPLE X Pretreatment of whollyaromatic polyamide paper with diethylene glycol, and subsequent dyeingwith a solution of ethylene glycol in dimethyl sulfoxide.

Samples of wholly aromatic polyamide paper (5.0 mil) were pretreatedwith diethylene glycol as described above in Example I, and then dyed asfollows:

The dye-bath, at 130C and atmospheric pressure, was made up as follows:

30.0 percent (by vol.) ethylene glycol 70.0 percent (by vol.) dimethylsulfoxide 8.0 percent grams per liter Basic Blue, Color Index The papersamples were dyed for 40 seconds, and then an after scour treatment wasgiven as described above in Example I. Good even dyeing was obtained.

EXAMPLE XI Pretreatment of wholly aromatic polyamide paper withtriethylene glycol, and subsequent dyeing with various blends ofethylene glycol, dimethyl acetamide, methyl ethyl ketone, dimethylsulfoxide, and dimethyl formamide with the simultaneous application ofultraviolet screeners:

Index No. 54 (10.0 grams per liter) for 40 seconds, and then an afterscour treatment was given as described above in Example I.

Well dyed paper products were obtained.

What is claimed is:

l. A process for the pretreatment of thermally stable shaped articlesderived from wholly aromatic polyamides for the purpose of improving thedyeability thereof, comprising subjecting said shaped articles to theaction of a high boiling glycol or glycol ether at an elevatedtemperature and under substantially anhydrous conditions.

2. The process as defined in claim 1, wherein the glycol or glycol etheris selected from the class consisting of the glycols: ethylene glycol,propylene glycol, diethylene glycol, dipropylene glycol, triethyleneglycol, tetraethylene glycol and the monoand di-lower alkyl ethers ofsuch glycols.

3. The process as defined in claim 2, wherein the monoand di-lower alkylethers are the methyl ethers.

4. A process as defined in claim 1, wherein the temperature of treatmentis from about to 500F.

2. The process as defined in claim 1, wherein the glycol or glycol etheris selected from the class consisting of the glycols: ethylene glycol,propylene glycol, diethylene glycol, dipropylene glycol, triethyleneglycol, tetraethylene glycol and the mono- and di-lower alkyl ethers ofsuch glycols.
 3. The process as defined in claim 2, wherein the mono-and di-lower alkyl ethers are the methyl ethers.
 4. A process as defineDin claim 1, wherein the temperature of treatment is from about 140* to500*F.